Lathe chucks generally have chuck jaws in the chuck body which are positionable in a direction radial to the chuck axis. It is also known to have the chuck jaws comprise two jaw segments, located one behind the other in the axial direction, these chuck jaws being movable in opposition to each other to various positions less than the maximum span of the chuck, in order to change the span of the chuck. It is further known to have the two jaw segments coupled with one another, and also to have a actuating member located axially in the chuck body and corresponding to the maximum possible span of the chuck, this actuating member being operatively connected to each axially rearward jaw segment and also having a positioning assembly for positioning the coupling member between two end positions, corresponding to the coupled and decoupled state of the jaw segments.
Lathe chucks of this type are disclosed, for example, in U.S. Pat. No. 3,682,491 and they make possible the convenient adjustment of chuck span, since in this case only the forward jaw segments are moved in the aforementioned decoupled state with respect to the rearward jaw segments. However, in the known lathe chucks, this movement can only be done manually and individually, one jaw at a time.